package com.hmdp.service.impl;

import cn.hutool.core.bean.BeanUtil;
import com.hmdp.dto.Result;
import com.hmdp.entity.VoucherOrder;
import com.hmdp.mapper.VoucherOrderMapper;
import com.hmdp.service.ISeckillVoucherService;
import com.hmdp.service.IVoucherOrderService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.RedisIdWorker;
import com.hmdp.utils.UserHolder;
import lombok.extern.slf4j.Slf4j;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.aop.framework.AopContext;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.connection.stream.*;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import javax.annotation.PostConstruct;
import javax.annotation.Resource;
import java.time.Duration;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Slf4j
@Service
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {
    @Resource
    private ISeckillVoucherService voucherService;
    @Resource
    private RedisIdWorker redisIdWorker;
    @Autowired
    private StringRedisTemplate redisTemplate;
    @Resource
    private RedissonClient redissonClient;

    private static final DefaultRedisScript<Long> SECKILL_ORDER_SCRIPT;

    private IVoucherOrderService proxy;

    private static final ExecutorService SECKILL_ORDER_EXECUTOR = Executors.newSingleThreadExecutor();

    @PostConstruct
    public void init(){
        SECKILL_ORDER_EXECUTOR.submit(new VoucherOrderHandler());
    }

    static {
        SECKILL_ORDER_SCRIPT = new DefaultRedisScript<>();
        SECKILL_ORDER_SCRIPT.setLocation(new ClassPathResource("seckill.lua"));
        SECKILL_ORDER_SCRIPT.setResultType(Long.class);
    }


    private class VoucherOrderHandler implements Runnable{
        String stream = "stream.orders";
        @Override
        public void run() {
            while (true){
                try {
                    // 1.从消息队列中获取消息 XREADGROUP GROUP g1 c1 COUNT 1 BLOCK 2000 STREAMS s1 >
                    List<MapRecord<String, Object, Object>> recordList = redisTemplate.opsForStream().read(
                            Consumer.from("g1", "c1"),
                            StreamReadOptions.empty().count(1).block(Duration.ofSeconds(2)),
                            StreamOffset.create(stream, ReadOffset.lastConsumed())
                    );
                    // 2.判断消息是否为空
                    if(recordList == null || recordList.isEmpty()){
                        // 如果为null，说明没有消息，继续下一次循环
                        continue;
                    }
                    // 3.不为空，有消息，处理消息
                    // 3.1.将消息解析成订单对象
                    MapRecord<String, Object, Object> entries = recordList.get(0);
                    Map<Object, Object> value = entries.getValue();
                    VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(value, new VoucherOrder(), false);
                    // 4.创建订单
                    handleVoucherOrder(voucherOrder);
                    // 5.ACK确认 XACK KEY GROUP ID
                    redisTemplate.opsForStream().acknowledge(stream, "g1", entries.getId());
                } catch (Exception e) {
                    log.error("处理订单异常" + e);
                    // 处理异常消息
                    handlePendingList();
                }
            }
        }

        private void handlePendingList() {
            while (true){
                try {
                    // 1.从pending-list中获取异常消息 XREADGROUP GROUP g1 c1 COUNT 1 STREAMS s1 0
                    List<MapRecord<String, Object, Object>> recordList = redisTemplate.opsForStream().read(
                            Consumer.from("g1", "c1"),
                            StreamReadOptions.empty().count(1),
                            StreamOffset.create(stream, ReadOffset.from("0"))
                    );
                    // 2.判断消息是否为空
                    if(recordList == null || recordList.isEmpty()){
                        // 如果为null，说明没有异常消息，结束循环
                        break;
                    }
                    // 3.不为空，有消息，处理消息
                    // 3.1.将消息解析成订单对象
                    MapRecord<String, Object, Object> entries = recordList.get(0);
                    Map<Object, Object> value = entries.getValue();
                    VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(value, new VoucherOrder(), false);
                    // 4.创建订单
                    handleVoucherOrder(voucherOrder);
                    // 5.ACK确认 XACK KEY GROUP ID
                    redisTemplate.opsForStream().acknowledge(stream, "g1", entries.getId());
                } catch (Exception e) {
                    log.error("处理pending订单异常" + e);
                    try {
                        Thread.sleep(20);
                    } catch (Exception ex) {
                        throw new RuntimeException(ex);
                    }
                }
            }
        }

        private void handleVoucherOrder(VoucherOrder voucherOrder) {
            Long userId = voucherOrder.getUserId();
            // 创建锁对象使用分布式锁,在这之前redis已经做过判断，这里加锁是为了以防万一，兜底
            RLock redisLock = redissonClient.getLock("lock:order:" + userId);

            // 获取锁
            boolean isLock = redisLock.tryLock();
            // 判断获取锁是否成功
            if(!isLock){
                log.error("不允许重复下单");
                return;
            }
            try{
                // 注意：由于是spring的事务是放在threadLocal中，此时的是多线程，事务会失效
                proxy.createVoucherOrder(voucherOrder);
            }finally {
                // 释放锁
                redisLock.unlock();
            }
        }

        // 线程池处理订单,使用阻塞队列
        //        private BlockingQueue<VoucherOrder> orderTasks = new ArrayBlockingQueue<>(1024 * 1024);
//        @Override
//        public void run() {
//            while (true){
//                try {
//                    // 1.获取队列中的订单信息
//                    VoucherOrder voucherOrder = orderTasks.take();
//                    // 2.创建订单
//                    handleVoucherOrder(voucherOrder);
//                } catch (InterruptedException e) {
//                    log.error("处理订单异常" + e);
//                }
//            }
//        }
    }

    @Override
    public Result seckillVoucher(Long voucherId) {
        // 获取用户
        Long userId = UserHolder.getUser().getId();
        long orderId = redisIdWorker.nextId("order");
        // 1.执行lua脚本
        Long result = redisTemplate.execute(SECKILL_ORDER_SCRIPT,
                Collections.emptyList(),
                voucherId.toString(), userId.toString(), String.valueOf(orderId));
        // 2.判断结果是否为0
        int i = result.intValue();
        if(i != 0){
            // 2.1.不为0 ，代表没有购买资格
            return Result.fail(i == 1 ? "库存不足" : "不能重复下单");
        }
        // 3.获取代理对象
        proxy = (IVoucherOrderService) AopContext.currentProxy();
        // 4.返回订单id
        return Result.ok(orderId);
    }


    @Transactional
    @Override
    public void createVoucherOrder(VoucherOrder voucherOrder){
        // 5.判断用户是否已经购买过
        Long userId = voucherOrder.getUserId();

        int count = query().eq("user_id", userId).eq("voucher_id", voucherOrder.getVoucherId()).count();
        if (count > 0) {
            // 用户已经购买过
            log.error("用户已经购买过");
            return;
        }
        // 6.扣减库存
        boolean update = voucherService.update().
                setSql("stock = stock - 1").
                eq("voucher_id", voucherOrder.getVoucherId()).
                gt("stock", 0).
                update();
        if(!update){
            log.error("库存不足");
            return;
        }

        save(voucherOrder);
    }


    // 这是之前的代码,同步进行秒杀下单
    //    @Override
//    public Result seckillVoucher(Long voucherId) {
//        // 1.查询优惠券
//        SeckillVoucher voucher = voucherService.getById(voucherId);
//        // 2.判断秒杀是否开始
//        if (voucher.getBeginTime().isAfter(LocalDateTime.now())) {
//            return Result.fail("秒杀尚未开始");
//        }
//        // 3.判断秒杀是否结束
//        if (voucher.getEndTime().isBefore(LocalDateTime.now())) {
//            return Result.fail("秒杀已经结束");
//        }
//        // 4.判断库存是否充足
//        if (voucher.getStock() < 1) {
//            // 扣减库存
//            return Result.fail("库存不足");
//        }
//        Long userId = UserHolder.getUser().getId();
//        // 创建锁对象 这个代码不用了，因为我们现在要使用分布式锁
//        // RedisLock redisLock = new RedisLock("order:" + userId, redisTemplate);
//        RLock redisLock = redissonClient.getLock("lock:order:" + userId);
//
//        // 获取锁
//        boolean isLock = redisLock.tryLock();
//        // 判断获取锁是否成功
//        if(!isLock){
//            return Result.fail("不允许重复下单");
//        }
//        try{
//            // 获取代理对象,因为是使用了事务,所以需要获取代理对象
//            IVoucherOrderService proxy = (IVoucherOrderService) AopContext.currentProxy();
//            return proxy.createVoucherOrder(voucherId);
//        }finally {
//            // 释放锁
//            redisLock.unlock();
//        }
//
//    }
}
